Thus far, robots with magnetic coupling have been fitted with wheels which are made, at least externally, in contact with the surface, of permanent magnets or electromagnets.
Prior art solutions exhibit one notable disadvantage. Whilst being able to function, they require enormous power to drive the wheels in order to overcome the magnetic field which tends to immobilize the wheels. It is therefore difficult to achieve free-sliding movement along the surface being inspected.
Moving the robot requires a powerful electric motor and therefore the need of electrical wiring to a remote power source, making the robot heavy and cumbersome.